[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

strings/zigzag_conversion.py

@@ -49,4 +49,4 @@ def zigzag_convert(s: str, num_rows: int) -> str:
 if __name__ == "__main__":
     import doctest
 
-    doctest.testmod()
+    doctest.testmod()